Make a paper cross (Fig. 251) into a double ring by joining opposite arms along their outer

Make a paper cross (Fig. 251) into a €œdouble ring€ by joining opposite arms along their outer edges (without twist), one ring below the plane of the cross and the other above. Show experimentally that one can choose any four boundary points A, B, C, D and join A and C as well as B and D by two non intersecting curves. What happens if you cut along the two curves? If you make a half-twist in each of the two rings and then cut?

Transcribed Image Text:

ь А в ь